Hydraulic system for automatic machines



F 5, 1935. w. J. GUILD ETAL HYDRAULIC SYSTEM FOR AUTOMATIC MACHINES 3 Sheets-Sheet; 1

W. J. GUILD ET AL HYDRAULIC SYSTEM FOR AUTOMATIC MACHINES Feb. 5, 1935;

3 Sheets-Sheet 2 Filed Feb. 16, .1932

v Zlnuenl' 014 Waldo J. Guild Harv Ostlund.

Feb. 5, 1935. w. J. GUILD ET AL 1,989,857

HYDRAULIC SYSTEM FOR AUTOMATIC MACHINES Filed Feb. 16, 1932 3 Sheets-Sheet 3 A V, gwvmflozd 48 V I waldo 3. Guild.

Ham" E.

Patented Feb. 5, was

iJNiTED STATES PATENT OFFIE HYDRAULIC SYSTE M FOR AUTOMATIG NES MACH] sachusetts Application February 16, 1932, Serial No. 593,326

16 Claims.

The present invention relates to hydraulic mechanisms for automatic machines and particularly to machines in which the movements of a vertical slide member are controlled by a fluid under pressure.

The copending application of Ostlund, one of the present applicants, Serial No. 555,747, filed August 7, 1931, now Patent No. 1,962,459, dated June 12, 1934, discloses a machine in which a heavy vertically movable slide member is held in any desired position of rest by fluid under pressure independently of the leakage in the slide actuating mechanism, and in which the slide is automatically reciprocated vertically by fluid under pressure in such a manner that the rate of upward movement is equal to the rate of downward movement. Such vertically movable slides are generally provided with mechanism by which they may be moved manually in order to position the tool in setting the machine for a particular operation. Especially in heavy slides the gear ratio between the slide and the hand wheel by which the slide is actuated must necessarily be rather great in order to permit the slide to be actuated by rotation of the hand wheel. Since such reduction gearing is not generally reversible, that is, the gear ratio is such that movement of the slide will not procure a correspondingrotation of the hand wheel, stripping of the gears will necessarily result from automatic reciprocation of the slide while the manually actuating mechanism is connected to the slide. It is accordingly the principal object of the present invention so to interlock the mechanism by which the slide is manually actuated with the mechanism'by which the slide is automatically reciprocated that only one of these mechanisms may be operatively connected to the slide at one time.

According to the present invention, the mechanism which controls the automatic reciprocation of the slide must be rendered inoperative before the manually actuating means may be connected to the slide and the manually actuating means having been connected, the automatic reciprocating mechanism cannot again be operative until 3 is a view of the control mechanism by I which the vertical slide is actuated, certain of the parts being in section and the individual parts of the mechanism being diagrammatically interconnected.

Fig. 4 is a view partly in section of a portion of the control mechanism showing the main control valve.

Fig. is a sectional view of the valve by which the mechanism for manual actuation of the slide is connected to said slide.

Fig. 6 is a diagrammatic view of the fluid pressure system which controls the slide.

Like reference characters refer to like parts in the difierent figures.

Referring to Fig. 1, the machine comprises a base 1 supporting'a carriage 2 on which the work is to be mounted, said carriage being suitably movable on ways 3, Fig. 2. The base is provided with an upstanding portion 4 to the upper end of which is secured a slide 5 mounted for vertical reciprocation on slideways,'not shown. The slide 5 is arranged to support a wheelhead 6 in which is mounted a shaft 7, the lower end of said shaft carrying a grinding wheel or other tool 8 and the upper end of which is connected to a motor 9 carried on the slide and arranged to procure rotation of the tool 8.

As disclosed in the above noted Ostlund application Serial No. 555,747, the slide 5 is arranged to be mechanically actuated by fluid under pressure which is directed alternately by a reversing valve 10, Fig. 6, to opposite ends of a cylinder 11 mounted in the upstanding portion 4 of the base. The cylinder receives a piston therein on the lower end of a piston rod 12, and the upper end of said piston rod projects beyond the cylinder and is connected to a lug 13 on the slide 5.

Referring now to Fig. 6, fluid under pressure is supplied to the reversing valve 10 by a pump 14 which is connected by a supply pipe 15 to the inlet port 16 of a casing 17 for the control valve 17 which casing also has an outlet port 18 connected by a, pipe 19 to the inlet port 20 of the casing 21 for the reversing valve 10. In addition to the inlet port 20, the reversing valve casing 21 has an exhaust port 22 and outlet ports 23 and 24, the latter being connected by pipes 25 and 26 to upper and lower ends of the cylinder 11 respectively. Channels 27 and 28 are provided in the valve 10 to connect the inlet port 20 alternately to the outlet ports 23 and 24 and at the same time to connect the opposite outlet port to the exhaust port 22, thereby directing fluid under pressure alternately to opposite ends of the cylinder. The

2 1 assess? inlet port 16 of the casing 17 for the control valve 17' comprises in the actual construction of the machine as shown in Fig. 4 intersecting channels 16 to the end of which the supply pipe 15 is connected.

The position of the reversing valve 10 is controlled -by mechanism of the type disclosed in Patent No. 1,582,468, granted April 2'7, 1926, to Heald and Guild, the latter being one of the present applicants. Referring to Fig. 1, the reversing valve 10 is actuated by a reversing lever 29 which is moved back and forth in response to the movement of the slide by reversing dogs 30 carried by said slide, thereby to establish fluid connection from the pump 14 alternately to opposite ends of the cylinder to procure a reciprocatory movement of said slide.

The slide 5 is brought to rest by closing of the outlet port 18 in the control valve casing 17 by movement of the control valve 17' to cut off the supply of fluid under pressure to the reversing valve 10. As shown in Figs. 4 and 6, the valve 1'7 has a longitudinal groove 31 therein which is in alinement with and provides fluid connection between the outlet port 18 and an exhaust port 32 provided in the casing 1'? for the control valve when the valve 17' is in closed position to permit the pressure fluid to exhaust from either end of the cylinder during manual actuation of the slide, since, as shown in Fig. 6, one end of the cylinder will be connected to the inlet port 20 of the reversing valve in -either position of said reversing valve and the fluid must exhaust from this end of the cylinder through the ports 18 and 32 during manual movement of the slide.

As pointed out'in the Ostlund application, a valve mechanism in the lower end of the cylinder 11 causes the slide 5 to move at the same rate of speed in both directions of travel, as best shown in Fig. 6. The fluid from the reversing valve 10 through the pipe 26 enters the lower end of the cylinder 11, as the slide is moving upwardly, past a downwardly closing valve 33 which is held against its valve seat by a coil spring 33'; said valve 33, is closed by said spring when the pressure fluid is exhausting from the lower end of the cylinder as the slide moves downwardly, and an upwardly closing valve 34 provided in the lower end of the cylinder permits the pressure fluid to exhaust from the lower end of the cylinder into the pipe 26. The upwardly closing valve 34 is held against the valve seat by a coil spring 35 which is adjusted to hold said valve 34 against opening until the pressure thereon is equal substantially to twice the pressure necessary to support the slide, that is, the valve 34 will open when the fluid ressure above the piston urging the piston do wardly' is slightly greater than the weight of he slide, since this pressure, in addition to the dead weight of the slide results in a pressure enough greater than twice the weight of the slide to overcome the friction of the slide parts and to open the valve When fluid is directed to the lower end of the cylinder to urge the piston upwardly, there is no resistance to the exhaust of fluid from the upper end of the cylinder and the pressure necessary to raise the slide will obviously be a. pressure equal to the weight of the slide, and such additional pressure as is necessary to overcome the frictional resistance of the slide to movement, this pressure corresponding to the necessary fluid pressure required to be exerted on the upper side of the piston to urge the slide downwardly. Since the actuating fluid is maintained at this desired pressure by a relief valve 36, Fig. 6,

valve 17 at which time the lower end of the cylinder is connected to the source of fluid pressure so that the slide is maintained in position without any downward movement thereof due to leakage of fluid out of the cylinder. To this end, as shown in Fig. 6, the fluid pump 14 is connected by a pipe 3'? to a port 38 in a casing 39 for a valve 40, which is provided with intersecting channels 41, the three ends of which, in the position of the valve shown in Fig. 6, coincide with the inlet port 38 and the outlet ports 42 and 43 in the casing 39, said ports 42 and 43 being connected respectively to the lower end of the cylinder 11 and to a relief valve 44 by pipes 45 and 46. The relief valve 44 is adjusted for a pressure substantially equal to the fluid pressure necessary to support the weight of the slide and fluid passing from the pump 14 through the valve 40 to the lower end of the cylinder enters said cylinder at the pressure determined by said relief valve, thereby exerting a counterbalancing pressure on the under side of the piston substantially equal to the weight of the slide to support said slide against downward movement.

The control valve 1'7 and the valve 40, which are shown, in the diagrammatic view of Fig. 6, as separate valves connected by a link 47, are in reality formed on a single rotatable valve member 48, Fig. 4, and spaced longitudinally thereon, so that said, valves rotate as a unit. Thus closing of the valve 17 to bring the slide to rest establishes fluid connection through the valve 40 to admit fluid to the lower end of the cylinder for counterbalancing said slide, and opening of the valve 17' conversely closes the valve 40 so that the slide actuating mechanism is again operative as a separate mechanism. Furthermore, in the actual construction, the pipe 37 from the pump 14 to the inlet port 38 actually is the pipe 15 above noted, the pipe 3'7 representing the channel 37 of Fig. 4. As shown in this figure, the control valve casing 1'7 and the valve casing 39, which are represented as separate members in Fig. 6, are parts of a single casing in which the intersecting channels 16' and the channel 37' are formed.

The above mechanism is all clearly disclosed in the Ostlund application, above cited, and is not, of itself, the present invention. The latter involves the incorporation, with mechanism similar to the mechanism above disclosed, of elements by which the carriage may be reciprocated manually together with looking elements to prevent operation of the fluid pressure actuating mechanism while the manually actuating mechanism is in operative position.

As best shown in Fig. 2, the slide 5 is arranged to be manually actuated by rotation of a hand wheel 49 which is secured to the forward end of a shaft 50. A bevel gear 51 on the inner end of the shaft 50 meshes with a bevel gear 52 on the lower end of a shaft 53, and the latter shaft carries a worm 54 adjacent the upper end thereof which meshes with a worm gear 55, Fig. 3. Rotation of the hand wheel 49 procures rotation of the worm gear 55 through the above gear train, and thus rotates a pinion 56 which meshes with a rack 5'7, Fig. 2, provided on the slide 5 to raise or lower said slide. As shown in Fig. 3, the worm gear 55 is secured against rotation on a shaft 58 by keys 59 and cooperating key ways 60, said shaft being journaled in bearings 61 provided by a casing 62. The shaft 58 carries the pinion 56 on the outer end thereof so that rotation of the worm gear by the hand wheel 49 results in a corresponding rotation of the pinion 56.

The pinion 56 is normally out of engagement with the rack 57 in order to permit the slide to be mechanicallyactuated by the fluid actuating mechanism above set forth, and said pinion is placed in operative position by fluid under pressure. Referring to Figs. 3 and 5, the casing 62 which receives the worm gear 55, and provides journals for the shaft 58 which carries the pinion 56, is provided with a cylinder 63 surrounding the shaft 58 which receives a piston 64 mounted on said shaft 58, and the shaft 58 is slidable axially through'the bearings 61 and the hub of the worm gear to permit said pinion on the shaft 58 to be placed in operative or inoperative position, in response to movement of said piston 64 by fluid under pressure. The portion of the shaft 58 extending through and beyond the hub of the worm gear has a longitudinal bore 65 which receives a coil spring 65', one end of which engages the bottom of said bore and the other end engages a button 66 in the bearing 61, said button being held in position by a cap 67. The spring 65' normally urges the shaft 58 and therefore the pinion 56 toward the left into the dot-dash line position of Fig.'

3 in which the pinion is out of engagement with the rack and is inoperative.

As above stated, the pinion is placed in operative position by fluid under pressure. Referring to Fig. 5, a valve 68 is provided in a casing 70 and the valve stem 71 for said valve extends therefrom and carrieson its outer end a handle 72, the position of which is shown in Fig. 1. also Fig. 6, which is connected by a pipe 74 to the pipe 46 connecting the port 43 in the valve'casing 39 to the relief valve 44. An outlet port 75 in the casing 70 is connected to the outer or left hand end of the cylinder 63 by a pipe 76-; and an exhaust port 77 is also provided in the casing 70. The valve 68 is provided with a slot 78, best shown in Fig. 6, by which the outlet port 75 may be connected witheither the inlet port 73 or the exhaust port 77. With the handle 72in the position shown in Fig, 3, the valve 68 is in'the position shown in Fig. 6 in which fluid connection is provided from the inlet port 73 to the outlet port 75 and thence to the left hand end of the cylinder 63. Fluid entering the left hand end of thecylinder 63 urges the piston to the right against the pressure of the spring ,65, thereby carrying the pinion 56 to the right into the full line position of Fig. 3 in which the pinion is in engagement with the rack 57, so that the slide may be moved vertically by rotation of the hand wheel, as above pointed out.,

It will be noted here that fluid under pressure from the pump 14 is supplied to the cylinder 63 only when the control valve 17' and the valve 40 are in the position of Fig. 6, at which time the fluid under pressure is cut off from the reversing valve 10 and the slide is at rest. The connection of the inlet port 73 of the casing 70 to the pipe 46 leading to the relief valve 44 prevents the pinion 56' and thus the manually The casing 70 has an inlet port 73, see.

rest by rotation of the valves 17 and 40, and this rotation of the valves also renders the mechanically actuating mechanism inoperative.

The machine is also arranged to prevent the mechanically actuating mechanism from being rendered operative while the manually actuated mechanism is operative by locking the valve 17 in its closed-position against turning movement. Referring to Fig. 4, the valve member 48, which, as above stated, incorporates both the control valve 17' and the valve 40, is mounted in a control casing 80 on the upstanding portion 4 of the machine, said casing incorporating both the casing 17 and the casing 39 diagrammatically shown in Fig. 6 as two separate elements, as a part thereof. The valve stem 81 for the valve member 48 projects forwardly, to the left in Fig. 4, and carries on its outer or forward end thereof a handle or lever 82 by which the position of the valve member is determined. Within the control casing or box 80, the stem 81 carries a cam 83 secured to said stem, which cam, as shown in Fig. 3, is provided with spaced notches 84 and 85, and a fluid actuated plunger 86 carries a pin 87, which is arranged to engage the notch 84 to lock said cam and thereby the valve member 48 against rotation, said plunger being operative only when the manually actuated mechanism is connected to the slide 5.

Referring now to Figs. 3 and 6, the cylinder 63 is provided with an inlet port 88 midway of said cylinder, which is connected directly to the pressure side of the pump 14 by a pipe 89, and is also provided with an outlet port 90, which is connected by a pipe 91 to a port 92 in a cylindrical recess 93 in the control casing 80, and an exhaust port 94. The periphery of the piston 64 which is slidable in the cylinder 63 has an annular groove 95 which is arranged to provide fluid connection between the outlet port 90 and the exhaust port 94 or the inlet port, 88 selectively. With the piston 64 at the right hand end of the cylinder, the pinion 56 being then in operative position, fluid connection is provided from the pump 14 to the cylindrical recess 93, thereby urging the plunger 86 which is slidable in said recess toward the right to carry the pin 87 connected to said piston, into engagement with the notch 84 on the cam 83 to lock the valve member 48 against turning movement as above stated. From a consideration of Fig. 3, it will be noted that the actual construction involves channels 88' and 90 in the casing 62 which connect the ports 88 and 90 to the pipes 89 and 91, and a channel 94' which connects the exhaust port 94 to an exhaust pipe 94".

When the pinion 56 is disconnected from the rack 57, by turning the valve 68 to permit fluid to exhaust from the cylinder 63; the spring 65' then urges the piston 64 to the left, carrying the pinion 56 out of engagement with the rack 57, the pin 87 is withdrawn from the notch 84. To this end, the piston 64 in its left hand position, establishes fluidconnection between the outlet port 90 and the exhaust port 94 in the cylinder 63, whereby fluid is exhausted from the cylindrical recess 93, and the plunger 86 is urged to the left by a spring 86' which surrounds the pin 87 to withdraw said pin from engagement with the notch 84. The cam 83, as above stated, has, in addition to the notch 84, a second notch 85 which, as best shown in Fig. 3, is engaged by a spring-pressed plunger 96 slidable in a recess 97 in the control casing 80, said plunger causing the valve stem 81 to be rotated clockwise as the valves on said stem are brought into the position shown, thereby urging the handle 82 positively against a stop 98 on the front of the control casing so that the cam is positioned by said plunger 96 in order topermit the nctch 84 therein to be engaged by the pin 87.

From a consideration of" Figs. 1 and 2, it will be apparent that the entire control mechanism is accessible from the front of the machine. The handle 82, by which the position of the control valve 17' and the counterhalancing valve 40 is controlled, is on the front of the control casing 80, and the handle 72 for the valve 68, by which the piston is operated, extends outwardly from beside the hand wheel 49, the latter being also accessible from the front of the machine.

Referring to Fig. 6 in which the mechanism is in position for manual actuation of the slide, said slide being at present supported in rest position by fluid under pressure, the operation of the machine will be briefly summarized. In the position of the mechanism shown in Fig. 6, fluid under pressure from the pump 14 passes through the supply pipe 37 to the valve 40 and from the valve 40 through the pipe 45 tothe lower end of the cylinder 11, thereby supporting the slide in rest position. At the same time, fluid from the valve 40 is directed through the pipes 46 and 74 to the valve 68 passing through said valve into the pipe '76 to the left hand end oi the cylinder 63, thereby urging the piston and the pinion carried thereby to the right to place the pinion 56 in engagement with the rack 57 on the slide. With the piston moved to the right into the position shown, fluid under pressure is admitted from the pump 14 through the pipe 89 to the cylinder and through the outlet port 90 into the pipe 91 to the cylindrical recess 93 thereby to urge the plunger 86 to the right to carry the pin 8'7 into engagement with the notch 84 on the cam 83 locking the control valve 17' and the valve 40 against turning movement. It will be noted that before the fluid can enter the left hand end of the cylinder 63, the valve 40, as

above stated, must have been turned into theposition shown in order to permit fluid under pressure to be directed through the valve 6 8 to said cylinder so that the slide is at rest when the manually actuated mechanism is connected to said slide. The manually actuated mechanism being now connected to the slide, rotation of the hand wheel will procure movement of said slide.

When the slide has been moved by the manually actuated'mechanism to the desired position, the manually actuated mechanism is disconnected from the slide by rocking the valve 68 to allow fluid to exhaust through the exhaust port. '77 from the left hand end of the cylinder 63, the piston in said cylinder being urged to the left by the spring 65'. When the piston reaches the left hand end of stroke, the pinion 56 being then out of engagement with the rack 57, fluid connection is provided between the cylindrical recess 93 and the exhaust port 94 in the cylinder to permit exhaust of fluid from said recess, whereby the plunger 86 is carried to the left by the spring 95 to withdraw the pin 8'7 from the engaging the notch 85 to turn the valves 1'7 and 40 positively into the position shown. Subsequently, the pinion 56 is moved into engagement with the rack by turning of the valve 68. It'

since fluid cannot enter the valve 68, and that the mechanism for automatic actuation of the slide cannot be rendered operative while the pinion is in engagement with the rack, since the valve 17 is locked against turning movement.

We claim,

1. In a machine of the class described. a movable slide, fluid pressure actuated means to procure movement of said slide, valve means to cut off the flow of fluid to said fluid pressure actuated means, manually actuated means having an independent connection to the slide to procure movementof said slide, and automatically controlled means to lock said valve means in closed position while said manually actuated means are in operative position.

2. In a machine of the class described, a movable slide, fluid pressure actuated means to procure movement of said slide, valve means to cut off the flow of fluid to said fluid pressure actuated means, manually actuated means to procure movement of slide, means to connect said manually actuated means to the slide, and means responsive to actuation of said connecting means to lock said valve in closed position.

3. In a machine of the class described, a movable slide, fluid pressure actuated means to procure movement of said slide, valve means to out off the flow of fluid to said fluid pressure actuated means, manually actuated means to procure movement of said slide, means to connect said manually actuated means to said slide, and means actuated in response to movement of said connecting means into operative position to lock said valve means in closed position.

4. In a machine of the class described, a movable slide, fluid pressure actuated means to procure movement of said slide, valve means to cut off the flow of fluid to said fluid pressure actuated means, manually actuated means to procure movement of said slide, means to connect said manually actuated means to said slide, and means responsive to movement of said connecting means to operative position to lock said valve means in closed position. A

5. In a machine of the class described, a movable slide, fluid pressure means to actuate said slide, valve means to control the admission of fluid to said actuating means, manually actuated means to procure movement of said slide, connecting means normally in inoperative position to connect said manually actuated means to said slide, fluid pressure means to actuate said connecting means into operative position, and means responsive to closure of said valve means to provide a supply of fluid under pressure for actuation of said connecting means.

6. In a machine of the class described, a movable slide, fluid pressure means to actuate said slide. valve means to control the admission of fluid to said actuating means, manually actuated means to procure movement of said slide, connecting means normally in inoperative position to connect said manually actuated means to said slide, fluid pressure means to actuate said connecting means, and means responsive to movement of said connecting means to operative position for locking said valve in closed position.

'7. In a machine of the class described, a vertically movable slide, fluid pressure means to procure movement of said slide, fluid pressure means to support said slide in rest position, and a valve member to provide fluid connection alternately to said fluid pressure means, and means operable when said slide is supported in rest position to connect said slideto manually actuating means therefor, and to lock said valve member against movement.

I 8. In a machine of the class described, a movable slide, fluid pressure means to procure movement of said slide, valve means to control the admission of fluid under pressure to said means, manually actuated means to procure movement of said slide, means controlled by fluid under pressure to connect said manually actuated means to said slide, said connecting means being normally in inoperative position, means to admit fluid under pressure to actuate said connecting means in response to closure of said valve means, and means responsive to movement of said connecting means to operative position tolock said valve means in closed position. ,I

9. In a machine of the class described, a movable slide, power actuated means to procure movement of said slide, control means for connecting said power actuated means to the source of power, manually actuated means to procure movement of said slide, means for connecting said last mentioned means to said slide independently of the connection of the power means therei to, and automatically controlled means to lock said control means in disconnecting position while said manually actuated means are in operative position.

10. In a machine 01'' the class described, a'movable slide, power actuated means to procure movement. or said slide, control means for connecting said power actuated means to the source of power, manually actuated means to procure movement of said slide, means independently of the control means for connecting said manually actuated means to the slide, and means responsive to actuation of said connecting means to lock said control means in disconnecting posi- 11. In a machine of the class described, a movable slide, manually actuated means to procure movement 01' said slide, means to connect said manually actuated-means to the slide, power actuated means having an independent connection to the slide to procure movement 01 said slide, control meansior connecting said power actuated means to the source of power, and means for locking said control means out of connecting position when saidmanually actuated means are in operative relation to the slide.

12. In a machine 01 the class described, a movable slide, power actuated means to procure movement oi said slide, control means for connecting said power actuated means to a source of power, manually actuated means to procure movement of said slide, manually controlled means for connecting said manually actuated means to said slide, said last-mentioned connecting means being operative only when said control means are in disconnecting position, and means actuated in response to movement of said connecting means for locking said control means in disconnecting position.

13. In a machine of the class described, a movable slide, power means to actuate said slide, control means for connecting the power actuated means to a source of power, manually actuated means to procure movement of said slide, connecting means normally in inoperative position to connect said manually actuated means to said slide, fluid pressure means to actuate said connecting means, and means under the control of said controlmeans to cut oil the supply of fluid to said fluid pressure means while said control means are in connecting position.

14. In a machine of the class described, a movable slide, power means to actuate said slide, control means for connecting the power actuated means to a source of power, manually actuated means to procure movement of said slide, connecting means normally in inoperative position to connect said manually actuated means to said slide, fluid pressure means to actuate said connecting means, means under the control of said control means to cut oil the supply of fluid to said fluid pressure means while said control means are in connecting position, and means responsive to movement of said connecting means into operative position for locking said control means in disconnecting position.

15. In a machine of the class described, a movable slide, fluid pressure means to procure movement of said slide, valve means to control the admission of fluid under pressure to said means, manually actuated means to procure movement of said slide, means controlled by fluid under pressure for connecting said manually actuated means to said slide, said connecting means being normally in inoperative position, valve means to control the supply 01 fluid under pressure for ac-' tuation of said connecting means, said last valve means being opened in response to closure of said first valve means.

16. In a machine of the class described, a movable slide, fluid pressure means to procure movement of said slide, valve means to control the admission of fluid under pressure to said means,

manually actuated means to procure movement of said slide, means controlled by fluid under pressure for connecting said manually actuated means to said slide, said connecting means being normally in inoperative position, valve means to control the supply of fluid under pressure for actuation of said connecting means, said last valve means being opened in response to closure of said first valve means, and means responsive to movement of said connecting means into operative position for locking said first valve means in closed position.

- WALDO J. GUILD.

HARRY E. OSTLUND. 

